Filter unit construction



June 16, 1953 'A..E. BELL FILTER UNIT CONSTRUCTION Filed Jan. 11, 195oINVENTOR. ALBERT E-.BELL

ATTORNEYS Patented June 16, 1953 '""ioN,1rrDi STATES PATENT OFFCEvPurolator Products, Inc., Newark, N. J., a. corporation of Delaware fApplication January 11, `1950,.'Seria1No. 138,050

This' invention relates to filters and more particularly to replaceableelement typewnlter element renlls.

axis. The pleated tubular body heretofore used,

thereafter has had its ends sealed off with flat end discs that are alsoresin impregnated, these end discs being-secured to the ends of thepleats j 4'Clams. (Cl. 210-169) by a suitable resin oradhesive bond.VBecause of the thinness vof the end vedges fof theA pleats at theirjoints with the end discs, difficulty in making an effective bond hasfrequently been encountered, resulting in lack of necessary rigidity ofthe unit and also in radial displacement of improperly bonded pleatseither duringl shipment or use and consequent leakage.

The invention herein contemplated has among its objects and features,the 'elimination of improper bonds', the provision ofrigid rugged filterunit structuresand' the prevention of radial displacement ofgindividualpleats even if Valoosening of or defective bonding should result fromtransportation or use, and prevention of leakage.

AWith structure embodying the invention, the end discs are curled overthe ends of the pleated lilterbody during bonding, there-by preventingall convolutons or pleats from extending beyond edges of the end discsat any time and thereby preventing leaks at such places. seal can bemade between the end discs and the pleats or convolutions because moreof the cement is retained during and after bonding. In

' addition, greater strength results because of thek substantial cup`shape' of thefdiscs over the obviously weaker structure when a frameisused.

.Other objects and novel features will become apparent from thefollowing description and accompanying drawings wherein:

Fig. l is a vertical section through a replaceable filler unit embodyingthe invention;

Fig. 2 is a transverse section taken along the line 2-2 of Fig.'1;

Fig. 3 is a vertical section similar to that of Fig. l of a modiedconstruction; and

Fig. 4 is a vertical section of a third embodiment of the invention.

Referring to the drawing and rst to Fig. 1, I denotes generally areplaceable filter unit embodying the invention. This unit includes abody II of filter paper or the like, preferably impregnated with phenolformaldehyde resin solution as Also aV better is well' known in thisart. This" body is pleated to provide pleats I2 las shown in Fig'. 2Vand the pleated body formed `into a tubular body with the pleats I2extending substantially lradially as shown in Fig. 2. The internal holeI 3 of the said tubular body contains a lhelical coil I4' whose turnshave substantially the internal diameter of said body and Whichact asguides or spacers for the inner longitudinal folds I5 ofthe pleats` I2.An external perforated Wrapping or cover I6 optionally is wrapped aroundthe outer longitudinal folds I'Iof the pleats I2. Y v

End discs I8 and I9, preferably of similar resin impregnated paper, tobe mounted at'opposite ends of the pleated elementl are provided. yTheseend discs are both initially of larger diameter than the outer'ove'ralldiameter ofthe tubular element I i and respectively have center holes'20, 2| of smaller diameter than the hole I3.` In applying the end discsto the body II, the outer edges of the pleats I 2n are'rst coated with aphenol formaldehyde resin cement and the inner faces of the two'discsaresimilarly coated with a similar cement layer 22, 23. The twol discsarethen applied to the opposite end edges of the pleats I2 withtheircenters concentric with Vthe longitudinal axis' of hole I3. lPressureand heat are then applied to rmlypress the'end discs against the pleatedges and simultaneously `pressure is appliedY to theoverlappingportions I9 to turn these edges down-V of thev discs I8 andwardly around the outer and inner folds I'I and because of the cementlayers 22, 23 are bonded to the pleats of their respective inner andouter folds. The heat acts to polymerize and set the resin and firmlyhold the parts between which the'resin cement lies.

In the completed structure, the annularrims l24, 25, 2B, 2'I provide cupshape formation to the discs and being firmly bonded to theiolds-of thepleats I2 effectively increase the rigidity and strength of thebondedparts. Moreover, these rims act to maintain 'fixed positions ofthe ra- Y dially extending pleats and to prevent any radial displacementthereof either outwardly or inwardly of the xed body form, and therebypreperforated metal cylinder 3B serving substan` y tially the samepurposeas spring I4. The end discs l8a and 19a in their application tothe end edges of the pleats I2a, however, are merely turned down attheir outer peripheries forming the outer annular flanges 25a, 21a whichare bonded to the outer folds Ha of the pleats 12aV by thermosettingphenol formaldehyde resin cement 22a in the same way as anges 28 and 2T.Inner flanges corresponding to flanges 24 and 25 are omitted. A guidering 3i is suitably positioned at one end of the unit being held inplace suitably by the disc |9a. Similarly, a second guide ring 32 issuitably held in place at the other end of the unit by the disc 18a.This ring 32 has a bail or handle 33 to facilitate insertion and removalof the unit. As with the modification of Fig. 1, the rims 26a and 21arender the discs cuplike in shape and being firmly bonded to the foldsIla of the pleats I2a 'effectively increase the rigidity and strength ofthe bonded parts, and act to prevent radialdisplagcement outwardly ofany pleats that may loosen in transit or use of the n unit, therebypreventing leakage.

In the embodiment shown in Fig. 4, all parts bearing the same referencecharacters with added subscripts b correspond to those in Figs. 1 and 2.Herein, however, the end discs [8b and 19h in their application to theend edges of the pleats I2b are only turned down at the peripheries oftheir holes 2Gb and 2lb forming the inner annular rims or flanges 24h,Zb which are bonded to the inner folds b of the pleats 12b by thethermosetting phenol formaldehyde resin cement 22h in the same way asflanges 2li and 25. Outer rims or flanges corresponding to rims orflanges 26 and 21 are omitted.

As with the modification of Fig. 1, the rims 29h,

. 25h, being firmly bonded to the inner folds 15b of the pleats I2b,effectively increase the rigidity l and strength of the bonded parts andact to reduce likelihood of loosening and outward radial displacement ofany pleats during transit or use,

. and thereby prevent leakage.

While specific embodiments of the invention have been disclosed,variations in structural details within the scope of the appended claimsare L possible and are contemplated. There is no intention, therefore,of limitation to the exact Y details shown and described.

What is claimed is: 1. A replaceable filter unit of the characterdescribed comprising a pleated filter body of resinimpregnated paperarranged in tubular form and with the pleats extending substantiallyradially,

end discs of the same material as the filter body closing off oppositeends of the body, said discs being bonded by a thermosetting resinadhesive to opposite end edges of said pleats, said adhesive of thepleats in contact therewith.

2. A replaceable filter unit of the character described comprising apleated filter body of resin-impregnated paper arranged in tubular formand with the pleats extending substantially radially, end discs of thesame material as the filter body closing off opposite ends of the body,said discs being bonded by a thermosetting resin adhesive to oppositeend edges of said pleats, said adhesive lying between under faces ofsaid discs and corresponding end edges of said pleats in contacttherewith, and having turned down rims bonded adhesively by Ythermosetting resin adhesive to inner and outer folds of the pleats,said adhesive lying between inner faces of the turned down rims and thefolds of the pleats in contact therewith,

3. A replaceable filter unit of the character described comprising apleated flilter body of resinimpregnated paper arranged in tubular formand with the pleats extending substantially radially,

, end discs of the same'material as the filter body closing olf oppositeends of the body, said discs being bonded by a thermosetting resinadhesive to opposite end edges of said pleats, said adhesive lyingbetween under faces of said discs and corresponding end edges of saidpleats in contact therewith, and having turned down rims bondedadhesively by thermosetting resin adhesive to outer folds of the pleats,said adhesive lying between inner faces of the turned down rims and thefolds of the pleats in contact therewith.

4, A replaceable filter unit of the character described comprising apleated filter body of resinimpregnated paper arranged in tubular formand with the pleats extending substantially radially,

. being bonded by a thermosetting resin adhesive to opposite end edgesof said pleats, said adhesive lying between under faces of said discsand corresponding end edges of said pleats in contact therewith, andhaving turned down rims bonded y adhesively by thermosettng resinadhesive to inner folds of the pleats, said adhesive lying between innerfacesof the turned down rims and the folds of the pleats in contacttherewith.

ALBERT EDWARD BELL.

References cited in the nie of this patent UNITED sTATEs PATENTS NumberName Date 1,148,237 Kneuper July 2'7, 1915 2,218,339 Manning Oct. 15,1940 2,239,868 Williams Apr. 29, 1941 2,358,238 Lindblad Sept. 12, 19442,395,449 Briggs Feb. 26, 1946 2,571,059 Puschelberg et al. Oct. 9, 1951FOREIGN PATENTS Number Country Date 401,287 Great Britain Oct. 30, 1933

